A researcher would like to map the location of galE and trpA genes in a new species of bacterium that appears to be closely related to E. coli. He decides to use cotransduction, and generatesnappropriate donor and recipient strains. He is disappointed when cotransduction is not seen in his experiement. What is the most reasonable explanation for this situation?

#Question id: 5649

#Unit 5. Developmental Biology

From earliest to latest, the overall sequence of early development proceeds in which of the following sequences?

#Question id: 5650

#Unit 5. Developmental Biology

Thalidomide, now banned for use as a sedative during pregnancy, was used in the early 1960s by many women in their first trimester of pregnancy. Some of these women gave birth to children with limb and organ deformities, suggesting that the drug most likely influenced ________.

#Question id: 5651

#Unit 5. Developmental Biology

Growth and development of plant parts involves ________.

I) cell division to produce new cells

II) enlargement and elongation of cells

III) specialization of cells into tissues

#Question id: 5652

#Unit 5. Developmental Biology

What generalization can be applied to the pole plasm of Drosophila, the P-granules of C. elegans, the yolk-free vegetal cytoplasm of Xenopus, and the localized mRNA for vasa in zebrafish?

#Question id: 5653

#Unit 5. Developmental Biology

Why is meiosis required for germ cell formation, yet is never used by somatic cells?

#Question id: 5654

#Unit 5. Developmental Biology

Two human disorders, Prader-Willi syndrome and Angelman syndrome, occur when a small deletion in a specific region of chromosome 15 is contributed by either the father or mother, respectively. Why does this small deletion not behave as a recessive allele for either syndrome, that is, why is its loss not made up for by the good copy of the region on chromosome 15 contributed by the other parent?